Similarly, by rendering devotional service to Kṛṣṇa, one automatically satisfies the requirements for all other forms of worship and all other spiritual processes.” One who is faithful and firmly convinced of this is eligible to be elevated as a pure devotee.
There are three classes of devotees, according to the degree of conviction. The first-class devotee is conversant with all kinds of Vedic literature and at the same time has the firm conviction mentioned above. He can deliver all others from the pangs of material miseries. The second-class devotee is firmly convinced and has strong faith, but he has no power to cite evidence from revealed scriptures. The third-class devotee is one whose faith is not very strong, but by the gradual cultivation of devotional service he can be promoted to the second- or first-class position. It is said in Śrīmad-Bhāgavatam (11.2.45) that the first-class devotee always sees the Supreme Lord as the soul of all living entities. Thus in seeing all living entities, he sees Kṛṣṇa and nothing but Kṛṣṇa. The second-class devotee places his full faith in the Supreme Personality of Godhead, makes friends with pure devotees, shows favor to innocent persons and avoids those who are atheistic or against devotional service. The third-class devotee engages in devotional service according to the directions of the spiritual master, or engages out of family tradition, and worships the Deity of the Lord, but he has not cultivated knowledge of devotional service, and he does not know a devotee from a nondevotee. Such a third-class devotee cannot actually be considered a pure devotee; he is almost in the devotional line, but his position is not very secure.